Book contents
- Frontmatter
- Contents
- Preface
- 1 The concept of chance
- 2 The classical picture: What is the world made of?
- 3 Ways the world might be
- 4 Possibilities of thought
- 5 Chance in phase space
- 6 Possibilist theories of chance
- 7 Actualist theories of chance
- 8 Anti-realist theories of chance
- 9 Chance in quantum physics
- 10 Chance in branching worlds
- 11 Time and evidence
- 12 Debunking chance
- References
- Index
10 - Chance in branching worlds
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- 1 The concept of chance
- 2 The classical picture: What is the world made of?
- 3 Ways the world might be
- 4 Possibilities of thought
- 5 Chance in phase space
- 6 Possibilist theories of chance
- 7 Actualist theories of chance
- 8 Anti-realist theories of chance
- 9 Chance in quantum physics
- 10 Chance in branching worlds
- 11 Time and evidence
- 12 Debunking chance
- References
- Index
Summary
As we saw in the previous chapter, the Everett interpretation seems to dispense with probabilities in quantum mechanics. Instead of describing a world for which many things are possible, but only some of those possibilities are actualised, it suggests a world in which all possibilities actually happen. Moreover, this is something of which we can be absolutely certain.
Obviously, this does not straightforwardly fit our experience. We do not see multiple possibilities becoming actual. Whenever we measure a superposed particle, we observe only one property or another. Moreover, we have a very useful probabilistic rule to help us to predict what we will see. How can the success of this probabilistic rule be explained, if an Everett world does not involve any uncertainty?
There are two main moves that are employed in response to this challenge. The first – what I call Stage A – is to show that there is a relevant sort of uncertainty, even in a universe where we are certain that everything will happen. The second move – Stage B – is to try to vindicate the probability of the Born rule in particular. That is, to show that we should not merely be uncertain about the future, but that we have good reason to attach the particular probabilities dictated by the Born rule to the possible outcomes of a quantum experiment. We will consider these two stages in turn.
- Type
- Chapter
- Information
- A Philosophical Guide to ChancePhysical Probability, pp. 162 - 191Publisher: Cambridge University PressPrint publication year: 2012